As the popularity of the Global Positioning System (GPS), people's lives have been quietly infiltrated by the GPS in recent years. The technology of GPS is widely used for vehicle routing guidance and improving road safety. Without any correction or calibration, GPS may have errors of about 10-15 meters. A differential GPS (DGPS) technology is a traditional positioning correction technique. Although the DGPS may be reduced the error to 3-5 meters, however, the error correction systems (DGPS) require to set the physical entities such as the base station, the main control station, and a geostationary satellite. The implementation costs of physical entities of the error correction systems are expensive and the GPS device has to communicate with the main control station to obtain calibration data. DGPS broadcasts the correction information (for example, the positioning correction vector or the difference between virtual distances) to improve the positioning accuracy. The main sources of the positioning errors are atmospheric effects error (such as ionosphere and troposphere), ephemeris error, multipath errors, etc. DGPS may reduce the errors due to the atmospheric effects error and the ephemeris error, but may not reduce the multipath errors. In particular, multipath interferences in different locations by different satellites are not the same in a complex urban environment. In the case that the positioning correction information in DGPS may not provide the amount of correction of multipath errors, the positioning accuracy may not reach the lane level. Therefore, it's an issue on how to improve the positioning accuracy so as to implement applications of collaborative road safety, navigation and other applications of complex junctions.